The invention relates to a sealed lamp socket for a light means, particularly for fluorescent lamps.
In lamps having an increased degree of protection, dust, moisture or water has to be prevented by suitable means from penetrating into the socket. In particular, the electric connecting device for the lamp contacts has to be protected from moisture and water. This applies independently from the type of the light means. For fluorescent lamps or other bar-like light means to be contacted endwise, generally sockets are used which have a sleeve nut providing a seal at the glass tube of the fluorescent lamp. The sleeve nut is at its inside provided with an appropriate seal.
Such a lamp socket is disclosed, for example, in DE 94 05 817 U1. The socket has a socket housing which comprises a stationary first housing part and a screw arrangement which constitutes a second housing part. The screw arrangement, in turn, comprises a threaded ring, a spacer ring of a socket seal and a tube or lamp seal. Both housing parts enclose an inner chamber in which a connecting device for the contacts of a fluorescent lamp is arranged. Further, in the inner chamber a sealing ring is disposed which has essentially a hollow-cylindrical shape. The sealing ring comprises a rigid ring body, at whose rearward end facing the stationary housing part, an annular groove is formed for receiving a seal therein. On the other hand, the frontal end of the ring body is provided with a seating face which is oriented in the axial direction and on which sharp points are provided. These penetrate into a deformable sealing body. With the sealing body a conical portion of the rotatable housing ring is associated for pressing the sealing ring, when tightened, radially inward against the glass tube of a fluorescent lamp.
It is relatively expensive to manufacture the above-described arrangement. Further, in service, the sealing ring may become detached from the annular carrier which may lead to a faulty mounting. Also, moisture cannot be excluded from seeping through the boundary face between the ring carrier and the sealing ring.
DE 83 10 312 describes a lamp socket for fluorescent lamps, having a screw ring which is to be threaded onto a stationary housing part. The screw ring consists of a rigid, annular plastic body provided with an inner thread. Further, on the socket-side end of the annular body a groove is provided, into which an elastomer material is sprayed for forming a seal. The elastomer material further passes through axial channels of the annular body and, at the lamp-side end of the screw ring, forms a flexible closure. The latter extends radially inward up to an opening through which the lamp tube of the fluorescent lamp may be inserted.
Such a socket ring requires for the lamp tube a narrow-tolerance opening, to ensure that the socket ring can be relatively easily turned with respect to the lamp tube. Tolerances in the tube diameter of the fluorescent lamps, however, pose a problem. While the fluorescent lamps with a small over-size lead to a stiffly turnable screw ring, in case of an under-sizing leaks may appear.
It is accordingly the object of the invention to provide a lamp socket which is easy to manufacture and which may be handled reliably.